And he claims British voters are “ambivalent” about Brexit - lamenting both the Tory government and Jeremy Corbyn’s Labour party for ruling out a second referendum.

He says: “Given what is at stake, and what, daily, we are discovering about the costs of Brexit, how can it be right deliberately to take off the table the option of compromise between Britain and Europe so that Britain stays within a reformed Europe?”

Mr Blair claims the willingness among EU leaders to compromise and “meet us half way” has changed dramatically since they rejected all-but the smallest of concessions from David Cameron just a year ago.

President Macron’s election as French President has changed the “political dynamics of Europe” and reform is “now on Europe’s agenda", Mr Blair says.

He suggests Britain could form part of the EU’s “outer circle” along with other Eurosceptic countries.

Mr Blair’s latest attempt to talk up the prospects of blocking Brexit came as No.10 was forced to play down the significance of Brexit Secretary David Davis’ admission that Britain would have to pay a hefty EU divorce bill to get a good trade deal.

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But a spokeswoman for the Prime Minister yesterday clarified that the size of the bill was still under discussion with the EU.

Downing Street said: “Our position is we will need to discuss a fair settlement of rights and obligations.”

In his lengthy article for his own Institute for Global Change think tank, Mr Blair also slams Jeremy Corbyn for failing to endorse a ‘soft’ Brexit - describing Labour’s current opposition to staying in the single market as “essentially the same policy as the Government”.

Blair has slammed Corbyn for not doing enough to endorse a soft Brexit

But he praises the hard-left Labour leader for his surprising election performance - paying tribute to his “temperament in the campaign” and his success in winning over younger voters”.

But in a scathing warning of the consequences of a Corbyn-led government, Mr Blair wrote: “If a right wing populist punch in the form of Brexit was followed by a left wing populist punch in the form of unreconstructed hard left economics, Britain would hit the canvas, flat on our back and be out for a long count.”